How to Manually Set and Undervolt your CPU Vcore

Quick way to reduce your temperatures!

How to Manually Set and Undervolt your CPU Vcore 

 

Introduction

A lot of the time when people build their systems, they put it all together, install their OS and programs, and then finish there. However, there are various little tricks you can do to get a little more performance out of your system, as well as reduce the temperatures. In our last guide, we showed you how to manually set your memory frequency, timings and voltage. Now, we show you how to manually set and undervolt your CPU’s Vcore, which should help to reduce your processor’s temperature significantly, and may enable you to run your fans a little slower, leading to an overall quieter system.

 

Method

First off, you need to download CPU-z here. This shows you what frequencies and voltages your CPU, Memory, and various other components are running at. On the CPU tab, you should be able to see ‘Core Voltage’. The value shown here is the voltage set by Intel to ensure every CPU in that range will run correctly at the stock frequency. The chances are however, that your processor will be able to run at a significantly lower voltage than this, and so by manually undervolting it, your system will remain stable, but operate at a lower temperature.


How to Manually Set and Undervolt your CPU Vcore

 

Now you should download another program called OCCT here. This is a form of stress testing program which puts your CPU through its paces, and simulates a high level of stress to ensure your processor will always be stable. Once downloaded, run the program, select ‘Linpack mode’, then ‘Automatic’. Then choose to run the test for 30 minutes, with an ‘Idle Period’ of zero. Depending on whether your CPU has Hyperthreading or not, you may also need to select ‘Use all Logical Cores’. Then click ‘On’, and let it run for the 30 minutes you set. When the test has finished, on the right hand side of OCCT you’ll be able to see the maximum temperatures your CPU cores reached during the time (and take a note of the figures shown here).

Having done that, you can now restart the computer and enter the BIOS (this is usually done by tapping delete as you press the power button). From here, navigate to the ‘Overclock’ settings. This will probably be under a different name on your motherboard, so you may need to look around in the BIOS to find it. Now you’re on the overclock settings, scroll down the list until you find ‘CPU Core Voltage’, or ‘CPU VCore’. You may need to change a 'mode' setting to manual mode to enable you to change the core voltage.

How to Manually Set and Undervolt your CPU Vcore

 

You should now set the Core voltage to the original value you saw in CPU-z at the start, which in our case was 1.075v. This has now locked the voltage to that value, and so it won’t ever go over that (like it may have done during the initial OCCT test). Now press F10 to save your settings and exit the BIOS, and start up your computer again as normal.

 How to Manually Set and Undervolt your CPU Vcore

 

From doing this, you can now run OCCT again (this time for a few hours) to ensure the system is stable, and also you may find temperatures are a little lower. If it is stable (which it should be if you’ve used the initial value you saw in CPU-z), you can now continue to decrease your volts in small increments such as 0.025v until your system is no longer stable. You’ve now found the lowest voltage your system can be stable at.

 How to Manually Set and Undervolt your CPU Vcore

 

Finally, back to CPU-z, you can see the core voltage is now at the value you set it to. If you run OCCT again, you should hopefully find that your temperatures are a fair bit lower than they were previously. With our system, we managed to shave off 6 degrees Celsius from our initial test.

 

  How to Manually Set and Undervolt your CPU Vcore  

 

How to Manually Set and Undervolt your CPU Vcore

 

Considering the cost of this is merely a bit of time, saving 6 degrees Celsius in temperatures is a significant drop in our eyes. If you're running a stock cooler, or a low end cooler, you may be surprised by how much quieter your system will be, and also how much lower temperatures will be. In our system, we used a Corsair H100i - renowned for being one of the best CPU coolers available. With our 4670k at stock, our H100i won't have been pushed anywhere near the limit. However, with a lower end or stock cooler, where the cooler may be incapable of absorbing the heat generated by the processor, the temperature change between 'Auto' and the lowest voltage could be significantly more than ours.

If you have any questions or problems, feel free to ask over in the OC3D forums. 

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Most Recent Comments

09-01-2014, 05:17:49

tinytomlogan
http://www.overclock3d.net/gfx/artic...151743834l.jpg

We show you how to manually undervolt your processor which will reduce temperatures and allow you to lower your fan speeds, leading to a quieter PC!


Continue ReadingQuote

09-01-2014, 05:27:23

TheOuterOne
Very helpful tutorial, thanks!Quote

09-01-2014, 06:55:36

WYP
Very nice, good stuff to know. Nothing quite like lowering power consumption and temps.

I'll need to bear this in mind if i ever I need to build anyone a new rig.Quote

09-01-2014, 07:15:07

ShaunB-91
Good article, reminds me I still need to find my correct stock, only been through the lower and test phase once.Quote

09-01-2014, 08:33:18

Lazlo
Very helpfull. Always wanted to do this, but have never found the time to thoroughly inform myself on the topic.

TBH I thought it would be more complicated. Gonna' give it a go when I get home from work now that I know how to go about it.Quote

09-01-2014, 09:30:36

ramoine
This is the reason I joined up on the forum .

I'm fairly new to overclocking and this guide will come in very handy , thanks !Quote

09-01-2014, 11:07:33

jamesriley94
Just to add a little to this - been playing around with my own system last night/this morning.
Considering the most I do with my PC these days is browse the internet and watch films, there's never been much of a need to OC my 3960X or anything, and I've not really ever had the time since I got it.

Undervolted it this morning - 'Auto' volts set it to around 1.3v at stock clocks (3.9ghz turbo). After 30 mins of OCCT that managed to get the hottest core to 86 Degrees C.

After Undervolting, managed to get the volts down to 1.12v with the hottest core at 61 degrees.

Saving 25 degrees isn't half bad for something that's free and only takes a couple of hours.Quote

30-07-2014, 10:36:56

Bla
This is great, the temps of my 4670k have dropped about 10 degrees C with the stock cooler. I haven't been able to stress test properly using OCCT since my temps gets too high within minutes, but it seems to be stable after some gaming sessions and AIDA64 stress tests. Do you guys think AIDA64's stress test is good/heavy enough for stability testing?Quote

30-07-2014, 10:47:03

Puck
Quote:
Originally Posted by Bla View Post
This is great, the temps of my 4670k have dropped about 10 degrees C with the stock cooler. I haven't been able to stress test properly using OCCT since my temps gets too high within minutes, but it seems to be stable after some gaming sessions and AIDA64 stress tests. Do you guys think AIDA64's stress test is good/heavy enough for stability testing?

AIDA64 been recommended to me by members of the OC3D community over OCCT because OCCT was producing odd results with the Haswell chips.

Here is a link to that thread:

http://forum.overclock3d.net/showthread.php?t=65692Quote

30-07-2014, 11:28:34

Bla
Quote:
Originally Posted by Puck View Post
AIDA64 been recommended to me by members of the OC3D community over OCCT because OCCT was producing odd results with the Haswell chips.

Here is a link to that thread:

http://forum.overclock3d.net/showthread.php?t=65692
Thanks! I'll keep using AIDA64 for stress testing then Quote

10-02-2015, 15:43:13

bacm8
I'm facing a strange thing with my Maximus VI HERO and my 4670K, when I change the voltage in bios for example for 1.000V he just stay giving 1.087V, I tried to change between differents voltanges from that stock voltage to 1V and nothing change, in bios keep saying the voltage I entered, but in windows nothing change...
Any idea, I have the last bios version ..Quote

10-02-2015, 15:58:17

NeverBackDown
Quote:
Originally Posted by bacm8 View Post
I'm facing a strange thing with my Maximus VI HERO and my 4670K, when I change the voltage in bios for example for 1.000V he just stay giving 1.087V, I tried to change between differents voltanges from that stock voltage to 1V and nothing change, in bios keep saying the voltage I entered, but in windows nothing change...
Any idea, I have the last bios version ..
That's probably normal. LLC could just be raising it slightly.

My 3570k for example is set at 1v at 3.6ghz 24/7 in the bios and when i'm not gaming or benchmarking it stays anywhere from .972-.992. I'm never at 1v unless i'm stressing the cpu.Quote

10-02-2015, 16:29:59

bacm8
Quote:
Originally Posted by NeverBackDown View Post
That's probably normal. LLC could just be raising it slightly.

My 3570k for example is set at 1v at 3.6ghz 24/7 in the bios and when i'm not gaming or benchmarking it stays anywhere from .972-.992. I'm never at 1v unless i'm stressing the cpu.
Ah ok thanks for the tip! Quote

10-02-2015, 20:33:53

Master&Puppet
Quote:
Originally Posted by NeverBackDown View Post
That's probably normal. LLC could just be raising it slightly.

My 3570k for example is set at 1v at 3.6ghz 24/7 in the bios and when i'm not gaming or benchmarking it stays anywhere from .972-.992. I'm never at 1v unless i'm stressing the cpu.
Not quite right, LLC has no effect on the CPU vCore since Haswell because the iVR manages the power draw from within the CPU. But anyway, the figure typed into the motherboard is only a reference and the actual power supplied will be slightly different depending on the motherboard manufacturer's power reference table.

Quote

11-02-2015, 00:59:14

NeverBackDown
Quote:
Originally Posted by Master&Puppet View Post
Not quite right, LLC has no effect on the CPU vCore since Haswell because the iVR manages the power draw from within the CPU. But anyway, the figure typed into the motherboard is only a reference and the actual power supplied will be slightly different depending on the motherboard manufacturer's power reference table.

Well that changes things.. Didn't know that. I never had a chance to mess around with a haswell rig before. Though didn't Devils Canyon take that off die? Can't remember exactly..Quote

11-02-2015, 03:32:15

ShaunB-91
Glad this article was in the recent threads, needed it again. Had to restore my BIOS and can't remember how to undervolt the CPU off the top of my head.Quote

11-02-2015, 09:32:47

Master&Puppet
Quote:
Originally Posted by NeverBackDown View Post
Well that changes things.. Didn't know that. I never had a chance to mess around with a haswell rig before. Though didn't Devils Canyon take that off die? Can't remember exactly..
DC is basically Haswell. A few changes to the manufacturing process on the CPU and a few nice additions to the chipset but fundamentally Haswell and DC are the same. Both have iVRs.

The confusing comes with you having an ivy bridge rig and with Haswell + DC still having legacy controls. With ivy, I, like you basically used vCore and LLC to set the CPU.

Haswell is more complicated. LLC only applies to the motherboard, not vCore. VCore applies directly to the die but also the vRing voltage and cache frequency has been separated from the core (as it was with ivy) so that adds an extra step.Quote

11-02-2015, 13:44:19

NeverBackDown
Quote:
Originally Posted by Master&Puppet View Post
DC is basically Haswell. A few changes to the manufacturing process on the CPU and a few nice additions to the chipset but fundamentally Haswell and DC are the same. Both have iVRs.

The confusing comes with you having an ivy bridge rig and with Haswell + DC still having legacy controls. With ivy, I, like you basically used vCore and LLC to set the CPU.

Haswell is more complicated. LLC only applies to the motherboard, not vCore. VCore applies directly to the die but also the vRing voltage and cache frequency has been separated from the core (as it was with ivy) so that adds an extra step.
I know they are the same, i thought DC just moved the VR back onto the board. Makes more sense nowQuote

05-06-2015, 10:25:09

madness777
I've got my E8400 undervolted to 0.95v, completely rock solid!
Readout:
http://shrani.si/f/1Z/Cr/3WHG3AHk/that-voltage.pngQuote

05-06-2015, 15:47:42

Moonchild
Can I do this on my laptop, or is it limited on desktop mobos ? I suppose lower voltage will lead in lower power consumtion, resulting in better battery lifeQuote

05-06-2015, 15:58:43

d1974
Quote:
Originally Posted by Moonchild View Post
Can I do this on my laptop, or is it limited on desktop mobos ? I suppose lower voltage will lead in lower power consumtion, resulting in better battery life
It depends on the BIOS the laptop uses. AFAIK on most you can not change the voltage. Quote

05-06-2015, 21:40:59

NeverBackDown
Quote:
Originally Posted by Moonchild View Post
Can I do this on my laptop, or is it limited on desktop mobos ? I suppose lower voltage will lead in lower power consumtion, resulting in better battery life
Depends on the BIOS the manufactur uses. Some gaming laptops have open BIOS's, Asus would be the one off the top of my head. It really just depends, but yes lowering voltage will lead to an increase in battery life, I doubt it would be much though considering you couldn't probably get it to go any lower.Quote

06-06-2015, 05:15:03

Thelosouvlakia
I don't think that is is needed on a laptop. The laptop processors are already optimised for low power consumptionQuote

06-06-2015, 07:53:58

Wraith
Great stuff, I'll get to it later. Still running the 2133 Domi plats at 1333, the 4440 supports 1600 think it's about time I clocked this shizzle.Quote
Reply
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